Drains on Purged Panels

[jscottelwood]

My company is installing drain plugs on purged panels (enclosures) (Hoffman NEMA 4).

The enclosures are in a Class I, Division 2, Groups B and D environment. (Hydrogen)

Here is the question:

The purged panels are vented with a one way vent (flapper style) so no ambient atmosphere can enter upon failure of the purging system.

My company is using an ECD-15 universal vent/drain installed in a meyers hub for the draining method.

The meyers hub will allow approximately 1/2" of water to accumulate before spilling over the inside lip of the hub. (this is unacceptable)

I have therefore replaced the drain with a Crouse-Hinds ACDPEN/M20/15.

I am still wondering two things.

By whose authority and direction did we install drains in these panels to start with and can I get a one way drain that doesn't have to be screwed into a meyers hub to be installed?

I really don't want to have to modify the hub by drilling holes (horizontally) in its threaded base to allow water out.

Thank you,

Jeff E. (Fab. I & E Tech.)

 

[don_resqcapt19]

First, where is all of the water comming from? Second, with a sheet metal enclosure about the only thing that you could do to eliminate the hub is to have a coupling welded on to the bottom of the panel and screw the drain into the coupling.
Don

 

[petersonra]

How would water ever get into a pressurized enclosure in the first place?

Does a drain in a div2 pressurized enclosure need to be one way? Maybe Bob Alexander could answer that question.

I can't say I recall having ever seen a drain in a pressurized enclosure. But, I never went looking for one either.

 

[coulter]

My company is installing drain plugs on purged panels (enclosures) (Hoffman NEMA 4). ...The meyers hub will allow approximately 1/2" of water to accumulate before spilling over the inside lip of the hub. ...

Yeah that is a problem. I run into this quite a bit, but never with a pressurized enclosure. I'm assuming you know the box fills up to 1/2" before draining cause you have seen it - so I won't ask you why this is happening in a pressurized enclosure - it just is or it wouldn't be a problem.

...I have therefore replaced the drain with a Crouse-Hinds ACDPEN/M20/15...

I found an ACDPEBN, which if that is the one you meant, it looks good to me. The picture shows a castilated nut and a hole in the threaded portion of the body. Are you having to drill a hole lower in the body to get the water level closer to the bottom of the box??

...By whose authority and direction did we install drains in these panels to start with ...

Don't know that. It's a design decision. But if you are getting water in the enclosures, what alternative do you have?

... and can I get a one way drain that doesn't have to be screwed into a meyers hub to be installed?...

I've never seen one. Hoffman makes a breather drain that screws on the outside, but is is not a one way design. P/N ANMV6
http://www.hoffmanonline.com/stream_document.aspx?rRID=105771&pRID=6174
I've used these before on outside 4X boxes that collect up water, but as you cansee, they destroy the 4X rating. I tended to put these in whenever the techs are drilling holes in the bottom of the boxes to let the water out.

But, they probably are not rated for a mars acetylene atmosphere

carl

 

[kameele]

My first guess would be that they need to put a drier on the air system feeding the purge.

 

[coulter]

Interesting and good thinking. I never thought of that. Any purge air I used was from an instrument air source. Up here that usually means -100F dew point. As you pointed out, might not be the case everywhere.

carl

 

[bobgorno]

I think kameele is right on. Wet air. By adding a drain, there is more airflow, thus, with poor quality air, you increase the moisture. Forget the drain, make sure the pressurization is not lost thru the conduit entries, watch for bad gaskets and hinges that are askew Put low-point drains in the conduit systems entering the enclosure. Try entering from the sides thru a tee, with a drain on the bottom of the tee.

Add a dessicant canister at the purge and pressurization unit inlet, maybe even a self draining filter regulator.